1. Field of the Invention
This invention relates to a digital electronic still-video camera for imaging a subject, converting the video signal thus obtained into digital image data and recording the image data in a memory cartridge capable of being loaded and ejected at will, and to a playback apparatus for playing back and displaying the image data resulting from the imaging operation of the digital electronic still-video camera. The memory cartridge mentioned here has the shape of a case or a card incorporating a semiconductor memory and this term is intended to cover means such as a memory card.
2. Description of the Related Art
A camera of the kind described in the specification of Japanese Patent Publication (KOKOKU) No. 62-21310 is a known example of a recent electronic still-video camera. This known electronic still-video camera is adapted to convert a video signal representing the image of a subject into a digital quantity and to store the digital quantity as image data in an internal memory incorporated in the body of the camera. At playback, the image data is read out of the internal memory and sent to a playback apparatus via a connector. The playback apparatus converts the provided image data into a video signal and applies the video signal to a display unit. As a result, a still picture is displayed on the display unit.
In another example of an electronic still-video camera described in the specification of Japanese Patent Application Laid-Open (KOKAI) No. 59-183582, the image data is recorded in a memory cartridge capable of being loaded in and ejected from the camera body at will.
The first example of the electronic still-video camera mentioned above is convenient because it is unnecessary for the user to carry about a separate memory cartridge. However, the number of frames capable of being photographed is limited by the storage capacity of the internal memory of the camera, and it is not possible to perform photography beyond the number of frames decided by the storage capacity of the internal memory. Using an internal memory having a large storage capacity permits more photography but raises the cost of the camera. In addition, there is a limit upon the storage capacity of the internal memory, and therefore in practical use there is no assurance that the internal memory will always have the capacity to preserve all of the frames desired to be shot.
In the second example of the electronic still-video camera described above, an advantage is that preparing the necessary number of memory cartridges makes it possible to perform photography without any limitation being imposed on the number of frames that can be shot. However, the user must carry about a memory cartridge even if the number of frames planned on being shot is small. Furthermore, after a memory cartridge has been filled to capacity with the image data, photography cannot be performed unless the memory cartridge is exchanged for a new one.
Further, with the first example of the electronic still-video camera, a separate playback apparatus is necessary in order to read and reproduce the image data from the internal memory of the camera. Likewise, the second example of the electronic still-video camera requires a separate playback apparatus in order to read and reproduce the image data obtained by the camera and stored in the memory cartridge.
A disadvantage encountered above is that the playback apparatus for the first example of the electronic still-video camera and the playback apparatus for the second example of the electronic still-video camera have connectors of different types, and therefore the cameras cannot share the same playback apparatus. Accordingly, in a case where two types of electronic still-video cameras are used for photography, two types of playback apparatus also are required. This is inconvenient and disadvantageous in terms of handling and storage space. In addition, the fact that two types of playback apparatus must be purchased is costly and is a serious drawback economically speaking.